Field of the Invention
The present invention relates to an imprint apparatus and a method of manufacturing an article.
Description of the Related Art
Recently, as micropatterning of semiconductor devices is requested more and more, an imprint technique of transferring a micropattern (three-dimensional structure) formed on a mold has been disclosed in Japanese Patent Laid-Open No. 2005-286062 and Japanese Patent No. 4791597 and has received attention.
A case in which the imprint technique is applied to a semiconductor manufacturing technique will be explained. First, an uncured photo-curing resin is supplied onto a substrate (wafer). Then, the resin on the substrate, and a mold having a three-dimensional microstructure are brought into contact with each other (imprint). The resin is irradiated with light (ultraviolet light) and cured. As a result, the three-dimensional structure of the mold is transferred to the resin on the substrate. Etching is performed by using this resin as a mask, thereby transferring the three-dimensional structure to the substrate.
In an imprint apparatus using the imprint technique, the mold and substrate physically contact each other via the resin. When the mold is imprinted or released, a force is applied to the substrate to shift the substrate from a predetermined position (alignment position). If an imprint process is performed in the next shot region while the substrate shifts, a pattern cannot be overlaid accurately at an alignment position, decreasing the device yield.
To solve this, so-called die-by-die alignment is employed, in which before bringing a mold and resin into contact with each other, alignment of a substrate is performed for each shot region and then the mold is imprinted in a state in which misalignment of the substrate is canceled. In this alignment, a through-the-mold detection system (TTM detection system) is used to detect the mark of a mold and that of a substrate. In the imprint apparatus, an illumination optical system for irradiating a resin with ultraviolet light through the mold is arranged above the mold. The TTM detection system needs to be arranged not to interfere with the illumination optical system.
However, a head which holds the mold, a head driving cable, and the like are also arranged above the mold, that is, near the illumination optical system. Thus, the space where the TTM detection system is arranged is restricted. More specifically, the TTM detection system needs to be arranged not to interfere with the illumination optical system and ultraviolet light from the illumination optical system. The TTM detection system needs be arranged with a tilt from the optical axis of the illumination optical system. At this time, the TTM detection system has a Littrow configuration, and detects the mark of a substrate by receiving light diffracted at a Littrow angle on the substrate. In the TTM detection system having the Littrow configuration, a sufficiently large numerical aperture (NA) of the TTM detection system cannot be set owing to the configuration restriction, and light irradiating a substrate is limited to a range where the condition of the Littrow configuration is satisfied. It is therefore difficult for the TTM detection system to detect the mark of a substrate and that of a mold at satisfactory accuracy, and the alignment accuracy decreases.